ITU-T K.35 PDF

This Recommendation covers bonding configurations and earthing for equipment located at remote electronic sites such as switching or transmission huts, cabinets or controlled environmental vaults with only one level, a need for a.c. mains power service and a floor space of about 100 m² without an antenna tower on the roof of the building as well as nearby; but which are more substantial than small electronic housings, such as carrier repeaters or distribution terminals. Experience in the operation of electronic equipment enclosures shows that the use of a bonding configuration and earthing that are coordinated with equipment capability and with electrical protection devices has the following attributes:

– promotes personnel safety and reduces fire hazards;

– enables signalling with earth return (functional earthing);

– minimizes service interruptions and equipment damage caused by lightning, exposures to power lines and faults in internal d.c. power supplies;

– minimizes radiated and conducted emissions and susceptibility;

– improves system tolerance to discharge of electrostatic energy.

Within this framework, this Recommendation:

a) is a guide to bonding configurations and earthing of telecommunication equipment in electronic equipment enclosures;

b) is intended to comply with safety requirements imposed by [IEC 60364 series] or national standardizing bodies on a.c. power installations;

c) is intended for installation of new electronic equipment enclosures;

d) treats coordination with electrical protection devices, but does not provide details of protective measures specific to electronic equipment enclosures;

e) utilizes the shielding contribution of effective elements of the structure and its contents;

f) addresses the bonding of cable shields;

g) is intended to facilitate electromagnetic compatibility of telecommunication equipment;

h) does not include protection against lightning electromagnetic pulses (LEMPs).